The invention relates to a longitudinally guiding driver assistance system in a motor vehicle.
Basically many longitudinally guiding driver assistance systems further developed as speed control systems are already known, which automatically control the speed of the motor vehicle to a predefined desired or maximally permissible speed. In addition to these longitudinal control systems, currently longitudinal control systems expanded by a ranging control—so-called spacing-related longitudinally controlling systems or speed control systems—can already be purchased from some manufacturers. Such systems—offered, for example, by the applicant of the present patent application under the name “Active Cruise Control”—, make it possible to automatically guide the motor vehicle while maintaining a desired distance from the vehicle driving ahead at a desired or a correspondingly lower speed. When a distance sensing system mounted at the motor vehicle, which may operate particularly on a radar basis, detects in its own lane a target object or (motor) vehicle driving ahead, its own speed will be adapted—for example, by causing a suitable braking torque—to the speed of the motor vehicle driving ahead or of the target object, such that a distance control contained in the “active cruise control” or in the corresponding longitudinal control system automatically sets, depending on the situation, an appropriate distance from the motor vehicle driving ahead or the target object, and maintains this distance.
Furthermore, longitudinally guiding driver assistance systems further developed as so-called speed limiting systems are known, which prevent an exceeding of the permissible maximum speed set by the driver.
German Patent document DE 10 2012 211 967 A1 describes a combination of a speed limiting system and a speed control system, in which case, the permissible maximum speed of the speed limiting system can be applied, instead of the adjusted set speed, as the (new) desired or target speed for the speed control.
Finally, in newer vehicles, there are also driver assistance systems which detect, either from map data of a navigation system and/or by way of image processing, in an anticipatory manner, a speed limitation, and are capable of constantly, as soon as a speed limit has been reached, indicating the latter to the driver, so that, independently and as required, the driver can adapt his speed to the speed limit (for example, BMW Speed Limit Info).
From German Patent document DE 10 2008 018 421 A1, a driver assistance system is known for sending and receiving speed data and/or traffic density data for controlling a speed control system, which, by means of the received data, determines a permissible maximum speed and reports the latter to the driver by the output of corresponding information. The driver can apply this target of the permissible speed by a simple activation to his speed control system.
From the still unpublished German Patent Application DE 10 2014 215 673 A1, a longitudinally guiding driver assistance system is also known which, when an imminent event is detected that requires a speed reduction, determines a deceleration strategy and, at a defined point in time before the event has been reached, outputs prompt information to the driver for permitting the automatic implementation of the deceleration strategy. When the driver acknowledges the prompt information, an automatic implementation of the deceleration strategy is caused. The detection unit can detect or recognize a relevant event either on the basis of map data (for example, of a navigation device) or on the basis of camera data.
It is now an object of the invention to provide an improved driver assistance system having an offer display, which can be comprehended by the driver, for the automatic application of a new set speed.
This and other objects are achieved by a driver assistance system for a motor vehicle according to the invention having essentially a detection system for detecting currently applying and relevant events lying ahead, which require a change of the permissible maximum speed, and a function unit which determines a location-dependent point in time when a relevant event is recognized, while taking into account the location of the relevant event (and, as required, additional necessary information, such as a determined permissible maximum speed at the location of the relevant event, the differential speed between the vehicle and a determined new permissible maximum speed, detected clear travel or following travel, current or permitted deceleration operating modes of the vehicle, such as sailing operation, coasting operation, braking operation). When this point in time has been reached, the function unit initiates an output of prompt information for permitting an automatic adaptation of the currently permissible maximum speed to a new permissible maximum speed. When an event lying ahead is detected in time, ideally a deceleration strategy of the vehicle is determined for reaching the determined permissible new maximum speed (at least approximately) at the location of the relevant event. By way of the determined deceleration strategy, the location-dependent point in time to be determined will then, as a rule, be obtained, at which the output of prompt information for permitting an automatic adaptation of the currently permissible maximum speed or the output of prompt information for permitting an automatic adaptation of the currently permissible maximum speed to a new permissible maximum speed will be initiated.
When, in the case of an output of prompt information, a permission acknowledgment triggered (manually)—for example, by actuating an operating element—is detected, when adapting the permissible maximum speed (at least during clear travel), a triggering of the driving and/or braking sensor system is initiated while taking into account the new permissible maximum speed by the output of a corresponding desired acceleration value, so that, at least in the case of clear travel—and a possibly higher manually predefined permissible desired maximum speed—the vehicle speed is controlled to the new permissible maximum speed.
Events lying ahead may, for example, be temporary or permanent speed limitations, which are either indicated directly on traffic signs or can be derived therefrom according to the general traffic rules (in Germany, for example, the speed limit for driving through built-up areas is 50 km/h). Likewise, the event may also be one that terminates the speed limitation or at least increases it to a new maximum speed, which usually occurs, for example, when leaving a built-up area.
The (new) permissible maximum speed relevant to the longitudinally guiding driver assistance system at the location of the event lying ahead may either be the actually predefined new speed limit or a speed that deviates from the predefined new speed limit by a predefined amount in the upward or downward direction. In this case, the amount and the direction of the deviation may, for example, also be adjustable by the driver in a central vehicle menu. This new maximum speed can be transmitted directly to the function unit, or can only be determined in the function unit on the basis of the available information.
As an alternative or in addition, it is also contemplated that, on a route known to the driver, the driver himself defines speed limits according to the location by way of an interface inside or outside the vehicle. When traveling the route with the active longitudinally guiding system, these speed limits can correspondingly be taken into account as new maximum speeds. In this case, the driver can, for example, in advance also select whether he wants to always have all self-defined speed limits taken into account, or only speed limits selected corresponding to a rule (for example, on a certain route, for defined route categories, at a defined time of day, as a function of weather conditions, etc.) Several speed profiles may also be created for a defined route section, which will then be active corresponding to predefined rules (speed profile for good route conditions, speed profile for wet routes and/or speed profile for snow-covered routes).
The function unit can further be set up to initiate a retraction of the output of a prompt information when a permission acknowledgment is recognized. When a (manually) triggered refusal of the prompt information is detected, the Output of the prompt information is also retracted.
The invention is based on the following recognition: When a longitudinally guiding driver assistance system—further developed as described above—is activated (for the first time), in the case of longitudinally guiding systems known so far, the last used set speed is used as the set speed or as the (new) permissible maximum speed or the current speed is used as the permissible maximum speed. As a result of the possibility of detecting currently applying relevant events, which require an adaptation or, in the case of a first activation, as required, also a first-time predefinition—of the permissible maximum speed, it is provided according to the invention that the function unit is further designed for initiating, in the case of an activation of the longitudinally guiding driver assistance system, while taking into account a detected currently applying event and the permissible maximum speed determined on the basis of the detected currently applying event, a first output of a prompt information for permitting an automatic first setting of the currently applied permissible maximum speed as the new permissible maximum speed. A first setting is either an adaptation of the permissible maximum speed automatically defined with the activation of the longitudinally guiding driver assistance system or an actual first predefinition of a permissible maximum speed.
The function unit is advantageously designed for initiating the first output of the prompt information for permitting an automatic first setting of the currently permissible maximum speed immediately after the activation of the longitudinally guiding driver assistance system and availability of the relevant information for determining the permissible maximum speed. Or, it may be initiated only after a predefined (fixedly defined or variably definable) time interval and/or route interval after the activation of the longitudinally guiding driver assistance system.
In addition to the above-mentioned recognition, a particularly advantageous further aspect of the invention is based on a further recognition: When the vehicle equipped with the longitudinally guiding driver assistance system is situated, for example, a short distance before entering a built-up area, 100 km/h would first be offered to the driver as the new permissible maximum speed when the longitudinally guiding system is activated, although the entrance to the built-up area with a permissible maximum speed of 50 km/h is situated ahead. The acceptance of the offer would accelerate the vehicle to 100 km/h. Because of the imminent entering into the built-up area, the driver would be offered 50 km/h as the new permissible maximum speed still during the acceleration operation (or shortly after the acceleration operation). Such a prompting sequence would not be comprehensible to the driver.
In order to prevent such an implausible behavior of the longitudinally guiding driver assistance system, it is provided in an advantageous further aspect of the invention that the function unit is designed for initiating the first output of the prompt information for the first setting of the currently applying permissible maximum speed when activating the longitudinally guiding driver assistance system while taking into account a detected event lying ahead, which after the permission of the first-time setting of the permissible maximum speed requires a (re-)adaptation of the permissible maximum speed. In particular, the function unit may, for example, be designed for not initiating or preventing, after the activation of the longitudinally guiding driver assistance system, the first output of the prompt information for the first setting of the currently applying permissible maximum speed, when an anticipatory speed limit with a lower maximum speed is detected in the near future, thus, an event lying ahead, which competes with the current speed or, after the permission of the first setting, with the permissible maximum speed.
A competing event can be detected by evaluating many different parameters. In an advantageous further aspect of the invention, a competing event lying ahead will be detected, for example, when the competing event would require an adaptation of the maximum speed to a new maximum speed, which is lower than the permitted (new) maximum speed permitted after the permitting of the first setting of the permissible maximum speed, and/or when the current speed of the vehicle is lower than the permissible maximum speed determined on the basis of the current relevant event.
An event, which competes in this manner, can be detected, for example, as a function of a permitted determined deceleration strategy, for reaching the new permissible maximum speed determined on the basis of the (possibly competing) event lying ahead, and/or as a function of a permitted acceleration strategy for reaching the permissible maximum speed determined on the basis of the currently applying event. A competing event is recognized, for example, when the location-dependent point in time, at which a change could (at the earliest) take place very early with respect to time and/or location from an acceleration strategy first initiated or initiatable because of the actual event to a deceleration strategy to be initiated on the basis of the event lying ahead.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.